GOA (Gate Drive On Array) is to manufacture the gate driver on the array substrate by utilizing the Thin Film Transistor (TFT) liquid crystal display array process for achieving the driving method of scanning line by line.
Generally, the GOA circuit comprises a pull-up part, a pull-up controlling part, a transfer part, a pull-down part, a pull-down holding part and a boost part in charge of boosting voltage level. The boost part generally comprises a bootstrap capacitor.
The pull-up part is mainly in charge of outputting the inputted clock signal (Clock) to the gate of the thin film transistor as being the driving signals of the liquid crystal display. The pull-up control part is mainly in charge of activating the pull-up part, and is generally functioned by the signal transferred from the former GOA circuit. The pull-down part is mainly in charge of rapidly pulling down the scan signal (i.e. the voltage level of the gate of the thin film transistor) to be low voltage level after outputting the scanning signal. The pull-down holding circuit part is mainly in charge of maintaining the scanning signal and the signal of the pull-up part in an off state (i.e. the set negative voltage level). The boost part in mainly in charge of performing a second boost to the voltage level of the pull-up part for ensuring the normal output of the pull-up part.
With the development of the LTPS semiconductor TFT, the LTPS-TFT LCD also becomes the focus that people pay lots of attentions. Because the LTPS semiconductor has better order than amorphous silicon (a-Si) and the LTPS itself has extremely high carrier mobility which can be more than 100 times of the amorphous silicon semiconductor, which the GOA skill can be utilized to manufacture the gate driver on the TFT array substrate to achieve the objective of system integration and saving the space and the cost of the driving IC. However, as considering the LTPS-TFT, the single type (single N-type or single P-type) GOA circuit has issues that the structure is complex, and the circuit property is poor, and particularly the power consumption is large. Especially, as mentioning the application in the small and medium size field, the power consumption is an important index of the performance. Therefore, how to reduce the power consumption and strengthen the circuit structure and the stability of the entire performance has become an important agenda faced by the GOA circuit of LTPS semiconductor TFT.